Bastion because he can transform. That was actually my first introduction to Overwatch for the same reason. At the time, I enjoyed how him transforming radically changed how you had to think and play as Bastion. So of course that kind of individuality was stomped out when Overwatch 2 came around.
I didn’t even know Reinhardt was in the game at the time. I found out when I swapped to tank because no one else would. That was one of the best discoveries of my life.